JPS59192248A - Reticle - Google Patents

Abstract

PURPOSE:To enhance precision of a photomask by forming protrusions at the corners of a reticle pattern and specifying their lateral and longitudinal lengths on it. CONSTITUTION:A longitudinal side line 9a constituting a part of a reticle pattern 9 formed on an image magnified, e.g. by ten times is extended to form V- shaped protrusions 10. A photoresist face is ordinarily exposed to light past the reticle pattern 9 and a 1/10 contracting lens to obtain a resist pattern 11. The corners of the obtained resist pattern 11 become uncurved angular corners 12. The longitudinal and lateral lengths of the protrusions of the reticle pattern, (m), (n) are each preferably controlled to 0.1x-0.5xmum, where (x) is the magnification of the reticle to the photomask. The protrusions 10 may be arcuate or rectangular.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reticle used in manufacturing a No. 11 mask used in a semiconductor manufacturing process.

Usually, a step-and-repeater (hereinafter referred to as
It's called a repeater. ) is used to reduce the projection exposure of a desired pattern onto a photomask blank (hereinafter referred to as blank), which is not shown in FIG. 1 but is an exposure step. That is, when manufacturing a photomask using a repeater, a reticle 1 with a 10x image or a 5x image is placed on the original side, and a 1/10x or 115x reduction lens (hereinafter referred to as lens) 2 is used to produce a photomask. , the photoresist 4 coated on the blank 3 is subjected to reduction projection exposure. After this reduction projection exposure, through development, etching, and resist peeling, a pattern,
A blank with a pattern formed thereon is usually called a "photomask."

Conventionally, the pattern of a reticle used in the exposure process has a shape as shown in FIG. 2(A). That is, the reticle pattern 5 is created in the shape intended at the time of design using an electron beam exposure device or the like.
The corners 6 of the reticle pattern 5 formed the desired corners of the photomask after the exposure process.

However, using the conventional reticle pattern 5,
When the photoresist on the blank is subjected to reduction projection exposure in the exposure process, resist patterns (hereinafter referred to as resist patterns) are formed.

) is formed as shown in Figure 2 (b). That is, since the resolution of the lens is not infinite, the corners of the resist pattern 7 do not form the angles desired for the first mask, but instead become curved portions 8 with a certain radius of curvature. was there. For example, if a reticle with a 10x image and a 1/10 (8) lens were used, the curved portion 8 would have a resistance of about 2 μR. Roughly speaking, in the design of semiconductor devices, it is said that electrical fields are parallel. Based on the premise, the photomask pattern is rectangular and its corners are filmed so that they are not convex parts.In particular, in the case of MOS-IC, since the flow of electricity is flat, the corners of patterns such as gates are If the curved part has a certain radius of curvature, the electrical characteristics as intended by the design will be 1!
Failures may occur, such as not being able to

An object of the present invention is to provide a reticle for producing a photomask having a pattern in which the corners of the resist pattern are not curved portions, but are substantially the corners of the resist pattern.

The present invention provides a protrusion at a convex corner of a reticle pattern formed on a reticle, and the protrusion forms a resist pattern by reducing projection exposure of the reticle pattern onto a photosensitive material such as a photoresist on a blank. The resist pattern is characterized in that the protrusion is of such a size that substantially no protrusion is present in the resist pattern.

Hereinafter, one embodiment of the present invention will be described in detail using FIG. 3. FIG. 3(a) shows a reticle pattern 9 formed on a reticle with a 10x image, and a V-shaped protrusion 10 that is an extension of the vertical side 9a that constitutes a part of the reticle pattern 9. . The reticle pattern 9 has a vertical side 9a of 30 μm and a horizontal side 9b of 20 μm, and is substantially rectangular except for the projections. Further, the length n in the vertical direction of the protrusion 10 is 3μ, and the length n in the lateral direction is 2μ.
μ. FIG. 3(b) shows, for example, a glass substrate LE-3.
0 (Hoya Glass Co., Ltd., trade name), a chromium film and a photoresist are sequentially laminated on the photoresist surface, and the reticle pattern 10 is exposed to normal reduction projection exposure through a 1!10x lens of a repeater. A resist pattern 11 (3μ×2μ) made by the exposure process shown in FIG. The corners of the resist pattern formed corner portions 12 .

The present invention is not limited to the shape of the protrusion 11 of the above embodiments, but may be a V-shape extending diagonally, a rectangle, or a circle as shown in FIG. 4, FIG. 5, or FIG. The protrusion 11 may be arcuate or polygonal. Further, the shape of the projections 11 may be the same at all corners of the reticle pattern, or may be different shapes. For example, as shown in FIG. 3(a), there are four protrusions 10.
are all V-shaped with extended vertical sides 9a, but each of the four projections 10 is shaped like a V-shaped with extended vertical sides 9a.
It may be shaped like a letter, a V-shape with extended horizontal sides, an arc, or a rectangle. Next, the size of the protrusion of the reticle pattern of the present invention is as follows: In the above embodiment, the length m in the vertical direction is 3μ,
Although the lateral length n is set to 2 μm, the present invention is not limited to this, and it is sufficient that the protrusions do not substantially exist in the resist pattern after reduction projection exposure.According to experiments, the reticle pattern The length m in the vertical direction and the length n in the lateral direction of the upper protrusion may each be 0.1x to 5xμ (x the magnification of the nireticle to the photomask), and more preferably O,lx to 0 It is sufficient if it is .5×μ. For example, when performing reduction projection exposure using a 1710x lens using a reticle with a 10x image, the reticle pattern 1 as shown in Fig. 3, Fig. 4, Fig. 5, or Fig. 7 is used.
The length m in the vertical direction and the length n in the lateral direction of the protrusion 11 of 0 may each be 1 to 50 μm.

Further, in the above embodiments of the present invention, the reticle pattern has a rectangular shape with protrusions, but the reticle pattern is not limited to a rectangular shape and may be a polygon as shown in FIG. Protrusions may not be provided at the concave corners of the rectangle, but protrusions may be formed at the convex corners.

As described above, according to the present invention, by forming protrusions at the corners of the reticle pattern, the corners of the resist pattern can be prevented from turning into curved parts even when using the exposure process of normal reduction projection exposure. It is possible to substantially form the corner portions, it is possible to create a photomask pattern intended at the time of design, and it is possible to supply a highly accurate photomask.

[Brief explanation of drawings]

Figure 1 is a diagram schematically showing the exposure process of normal reduction projection exposure, Figure 2 (A) is a plan view of a conventional reticle pattern, and Figure 2 (B) is a resist pattern created using a conventional reticle pattern. 3(A) is a plan view of a reticle pattern which is an embodiment of the present invention, FIG.
b) is a plan view of a resist pattern created according to one embodiment of the present invention; FIGS. 4, 5, and 6 are enlarged partial plan views showing other embodiments of the protrusion of the present invention; FIG. 7 is a plan view showing the shape of another reticle pattern of the present invention. 1... Reticulation, 2... Reduction lens, 3...
Photomask blanks, 4... Photoresist, 5
... Conventional reticle pattern, 6. Corners of the conventional reticle pattern, 7. Photoresist pattern when using the conventional reticle pattern, 8. Curved portion, 9. Reticle pattern, 10...
A protrusion forming part of the reticle pattern of the present invention,
11... Photoresist pattern when using the reticle pattern of the present invention, 12... Corner part Figure 1 Figure 2 Figure 3 Figure 4 Figure 5rXJ Figure 6 Figure 7

Claims (3)

[Claims] (1) A protrusion is provided at the convex corner of the reticle pattern, and the size of the protrusion is such that the length m in the contraction direction and the length rl in the lateral direction on the reticle pattern are 0.1X to 5X.
μ (x magnification of the reticle) relative to the mask. (2) The redicle according to claim 1, wherein the protrusion has a V-shape. (3) The redicle according to claim 1, wherein the protrusion has a rectangular shape. (/I) The reticle according to claim 1, wherein the protrusion has an arcuate shape.